Means for avoiding damage through moisture in the low pressure part of steam turbines



June 21; 1932. N, HlLGERs 1,864,352

MEANS FOR AVOIDING DAMAGE THROUGH MOISTURE IN THE LOW PRESSURE PART OF STEAM TURBINES Filed Jan. 2. 1931 Fig l.

SPARK GAP F01? ION/Z/NG STE/4M Inventor Nino Hilgers,

by MW His Attorney- Patented June 21, 1932 PATENT OFFIC .NINO HILGERS, OF BERLIN-WEST'END, GERMANY, ASSIG-NOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK MEANS FOR AVOIDING DAMAGE THROUGH MOISTURE IN THE LOW PRESSURE PART OF STEAM TURBINES Application filed January 2, 1931, Serial No.

It is known that with too much moisture in the low pressure part of a turbine its i blading is considerably impaired through the influence of the water. Furthermore, the

1 efficiency of the machine is considerably decreased through moisture, the etficiency losses in the individual stages of the turbine increasing with increase in the moisture content of the steam.

It has been sought toovercome the harmful influence of the moisture by heightening the range of temperature of the steam in i the turbine, whereby the final moisture beture, however, can only beincreased up to a comes less. This is effected by increasing the live steam temperature and using intermediate heating. The live steam temperajuriousefiects of wet steam without the use of intermediate superheating whereby the corrosion of the blades is prevented or diminished with the simultaneous increase in the efliciency. The avoidance of an intermediate superheating also makes possible the use of higher pressures.

The causes of damage to the blades and decrease of the efliciency through wet steam are 'to be traced to the fact that the expanding steam in the turbine is partly condensed into small drops of moisture. The steam is accelerated in the nozzle and at the end of the nozzle has a greater velocity, while the small drops of water occuring in the steam, on account of their greater mass, at the end of the nozzle have no longer the same speed as the outflowing steam. The drops therefore, as a result of their lower velocity, strike the blades at an angle of incidence diifering from that in the case of the steam. Thus, they do not strike the front side but the rear of the blades,

and,in time bring about a destruction of the blades as well as a reduction of efliciency by braking effect. The greater the drop in velocity of the particles of water and the more obtuse their angle of incidence on to the 506,256, and in Germany January 2, 1930.

blades, the greater is the damage to the blades and loss of efliciency.

With a given specific weight of water, the velocity of the dropsat the'nozzle end mainly depends on the size oi the drops. According to-the equation for the velocity of falling of small drops. in gases, the velocit'y'of falling is dependent on the acceleration, the square of the diameter of'the particles and other less as small as possible. The smaller the volume of'the drops, thehigher becomes the velocity of the drops at the nozzle end and" the more acutethe anglerof incidence of the drops on to the blades. The damage to the blades thu'salso becomes smaller aswell as the brakingefiect, whilelt'he eiiiciency becomes greater.

The P formation of the drops, as is known, depends oni condensation nuclei in the steam or gas. The morecondensation nuclei there are, the ig reater becomesthe number of drops formed; With a; definite moisture of the steam,.therefore, with increased number of drops, thevolume of the individual drops becomesismaller:

Accordingto my invention, I increasethe number ofthedrops-of moisture'in the steam whereby the volume ofthe individual drops is diminished, Thisresult is obtained, in ac.- cordance with theinventiomin that condensation nuclei are artificially formed in or supplied] to. the steam. This may be accomplished either by the ionization of the steam or by the admixture of an ionized gas, for example, ionized air, with the steam. The ionizedairm'ay" be mixed with the flow of steam at any point of the turbine; case "of singl'e'stage" turbines", the ionized air may be introduced into the steam supply pipe, while in'the'case of multi stage turbines the ionized airmaybe supplied through a pipe connected to'an" intermediate stage of thaturbinm For ionizing the steam, it can In the use be conducted through a spark-gap. The the turbine, whereby the size of the drops of more the steam, or the gas mixed with it, is ionized, the more intensive is the production of condensation nuclei and the greater becomes the number of the drops of water with simultaneous decrease of the volume of the individual drops. It will be readily understood that the supply of ionized gas or the ionization of the steam itself causes the provision of an increased number of condensat1on nuclel or condensation centers, to the water which are formed is reduced.

In witness whereof, I have hereunto set my hand this 16th day of December, 1930.

NINO HILGERS. w

effect that more drops of water of a'smaller 7 size are formed than wouldbethe case without the provision of an increased number of nuclei. By condensation nuclei I mean solid or charged particles. 7 If the particles are charged, they induce in the steam particles a charge in the opposite sense and thereby attract the steam particles, causing condensation thereof, a phenomenon which is well known in physics. 'With my invention the efficiency of the turbine is increased while damage to the blades by the drops of water is avoided.

In the drawing, Figs. 1 and 2 show turbines embodying my invention.

Referring toFig. 1, 3 indicates a steam turbine of suitable design and 4 indicates a pipe through which ionized gas may be supplied to the turbine from any suitable source.- The pipe is shown as being connected to the admission end of the turbine, but it will be understoodcthat it may be connected to an intermediate stage if desired.

In Fig. 2, 5 indicates a steam turbine and 6 indicates a spark-gap of suitable design for eifecting ionization of steam. It is shown connected to an intermediate stage of the turbine but it will be understood that this is only by way of example and that any suitable arrangement may be used.

What I claim as new and desire to secure by Letters Patent of the United States, is

l. The combination with a steam turbine, of means for supplying ionized gas to the steam whereby the number of condensation nuclei for the steam is increased and the number of drops of water formed as the steam passes through the turbine is increased andthe size of the drops is decreased.

2. The combination with a steam turbine, of means for ionizing steam to increase the number of condensation nuclei in the steam whereby the number of drops of Water formed as the steampasses through the turbine is increased and the size of the drops is decreased.

3. The combination with a steam turbine, of a spark-gap located in the path of flow of steam for ionizing it whereby the number of condensation nuclei is increased.

A. The combination with a steam turbine, of means for increasing the number of condensation nuclei for steam passed through Isa"- 

